OneCAD/skills/solidcraft-editing/SKILL.md

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name: solidcraft-editing description: Use when changing, fixing or extending an existing SolidCraft design through its MCP server - a .solidcraft file or the design open in the app. Typical requests: resize it, move a cut, change a hole or standoff, add a fillet or chamfer, make a fixed value parametric, or a feature shows an error after a change or after the app crashed.

SolidCraft editing

Overview

Edit an existing design through its parameters instead of rebuilding it. Every sketch dimension and feature input is already a parameter (d1, d2, ...), so most edits are a parameters.change each, sent together in one batch. Map the design with a few compact calls rather than walking the timeline one feature at a time. For command shapes and traps, use reference.md from the solidcraft-modeling skill.

Map the design (3-4 calls)

1. Open: if the design is not open yet, run open {path}. When the server is bridged to the app and the current design is dirty, ask before opening anything.
2. Overview: inspect_design {"measure":false,"sketches":false} lists the user parameters, the sketch dimensions (d1, d2, ... with their expressions), the features in order, and their errors.
3. Feature inputs: execute parameters.list {"filter":"feature"} gives every feature input as an object such as {"name":"d9","expression":"(6) / 2","feature":"Cylinder1","input":"Radius"}. inspect_design leaves these out.
   • Match sketch dimensions by expression.
   • If that is ambiguous, sketch.inspect {sketch} that one sketch, which also shows its points in world coordinates.
4. Baseline: measure {}, so you can predict every change against it.

timeline.inspect {feature} is only for two cases:

• changing more than a number: profiles, direction, operation or edges
• checking whether a position follows a parameter, for example a cylinder base written as width/2 - wall - 6

Inspect one feature of each kind, not every copy.

Change

• A number: parameters.change {"name":"d9","expression":"..."}.

  • To make a fixed value parametric: add a user parameter first (parameters.add standoff_d), then set each input to an expression of it (standoff_d/2).
  • Several changes: one batch.

• A user parameter: set_parameter or parameters.change. Every expression that uses it follows.

• Structure: timeline.edit {"feature":..., "set":{...}}, with the field shapes timeline.inspect shows.

• A new feature goes at the end of the timeline. To place it earlier:

  1. timeline.roll_to {"position":N}. A position is safer than a name, since a sketch and a feature can share one.
  2. Add the feature.
  3. timeline.roll_to {} to return to the end.

  Everything after the insert recomputes, and a feature that worked can now fail. Seen: a corner fillet after an inserted chamfer.

• Risky or multi-step edits: take edit.checkpoint in its own call first. edit.restore_checkpoint {checkpoint} goes back exactly. A batch rolls itself back; separate execute calls do not.

• Deleting: timeline.dependents {feature} first. It lists what is deleted with it and what would fail.

• Ambiguous wording: "2 mm higher" on a value written as wall + 6 can be relative (wall + 8) or absolute.

  • Keep the design's intent, which is the relative reading.
  • Tell the user which reading you used. This matters most when the same request also changes wall, because then the two readings give different heights.

• New constants such as a chamfer size go in user parameters, so the user can change them later.

Verify

1. Predict, then measure once. Send the independent changes in one batch, predict the total volume change, then run measure once.
   • A move does not change the volume. To confirm a moved sketch, read its points' world coordinates with sketch.inspect. You can also predict the COM shift, Δcom = V_moved · Δz / V_body, but only when nothing else in that batch changes the volume.
   • If it matches to about 0.01%, you are done.
   • If not, restore the checkpoint, then apply the changes one at a time, measuring after each.
   • A cut or chamfer that leaves the volume unchanged has missed.
2. Timeline health: run inspect_design {"measure":false,"sketches":false}. Every error and warning must be null. If something broke, restore or undo before you try anything else.
3. Interior features: take one top-view screenshot, {"source":"model","view":"top","width":480,"height":320}. When the server is bridged, view also turns the user's camera. The iso view hides standoffs behind the walls.
4. Still parametric: if the user wants it kept parametric, change one driving size, measure, then set it back.

When something is already broken

• A feature has an error after opening: read it with timeline.inspect, fix the input or definition, and recompute.
• The app crashed:
  • crash_reports lists the reports, and crash_reports {id} gives the command that crashed.
  • execute doc.recovery_list and then doc.recover {id} reopen the autosaved design.
  • Never retry the crashing command unchanged.

Save

save {"path":"...-v2.solidcraft"} writes a copy. save {} overwrites the opened file; do that only when the user asked for it.

Red flags

Thought	Do instead
"timeline.inspect each feature to understand it"	parameters.list {"filter":"feature"} shows every input in one call.
"Delete and remodel the feature"	Change its dN input, or use timeline.edit. History and downstream picks stay intact.
"The insert worked, done"	Check the errors of every later feature.
"Edge points with expressions, so the chamfer follows the size"	They are rejected, and stored picks already follow size changes.
"Pick all 8 rim edges"	One pick on a tangent chain fillets or chamfers the whole chain.
"Measure after every edit"	One batch, one measure against the summed prediction. Split only when it misses.